A member of Parliament (government or opposition) who is not in a leadership role in their party but merely sits literally on the back bench.

1874 in the House of Commons sense, from back (adj.) + bench (n.); occupants of the rear seats being the least-prominent politicians.

Those Members of Parliament that are not part of the government, but are member of the party in government. They are supposed to support the government. They do not sit in the front seats of the House [..]

Members of Parliament on the government side who sit on the backbenches and are not in cabinet, or those similarly distant from shadow cabinet posts in opposition parties.

A Member of Parliament who is not a minister and does not sit on the front benches reserved for Cabinet Ministers or for opposition party officials.

Parliamentarians that do not hold ministerial or shadow ministerial office, also known as private members. Backbenchers generally have more freedom to speak as they are not as constrained by loyalty.

A "private member" who is not a minister, parliamentary assistant or leading member of the opposition. Historically, he or she occupied a back bench in the Legislative Chamber.

A Member who is not a Minister of Government, Leader of the House, Leader of the Opposition or a Whip. Distinguish: Private Member

(n) a member of the House of Commons who is not a party leader

A backbencher is a member of parliament who is not a minister or shadow minister. They occupy the rear benches of parliament and are not directly involved in the executive government.

(politics) A Member of Parliament who does not have cabinet rank, and who therefore sits on one of the backbenches or in one of the back rows of the legislature.